Bitburger Braugruppe is vegan friendly

Paraphrasing from their website (https://www.bitburger-international.com/news/news-details/news/were-often-asked-is-your-beer-vegan/, posted October 2017, retrieved April 2018):

Their beers are vegan friendly, however the labels on the bottles are attached with glue containing casein. Barnivore's stance on label glue as it pertains to the vegan friendly label is at http://www.barnivore.com/faq#glue but td;dr: if you're concerned about the label, drink from cans or kegs.

Company email (January 2014):
"We herewith confirm that Bitburger Pils is brewed according to the German Purity Law (Deutsches Reinheitsgebot). Therefore only malted barley, hops (not chemically treated) and water are allowed as ingredients. For fermentation a yeast is used.
Clarification of the beer is carried out by using diatomaceous earth and silica gel, products excavated from surface mines.

We do not use isinglass or other products coming from animals to classify our beers.

Bitburger beer is only brewed and filled in Germany."